Some electronic systems, such as magnetic position tracking systems, conduct electrical signals between an intra-body probe and a controller. The electrical signals are sometimes prone to parasitic voltage induced in the presence of magnetic fields. Various techniques may be used for improving the immunity of electronic systems to induced parasitic voltage.
For example, U.S. Pat. No. 5,371,469 describes a constant current loop measuring system for measuring a characteristic of an environment. The system comprises a first impedance positioned in the environment, a second impedance coupled in series with said first impedance and a parasitic impedance electrically coupled to the first and second impedances. A current generating device, electrically coupled in series with the first and second impedances, provides a constant current through the first and second impedances to produce first and second voltages across the first and second impedances, respectively, and a parasitic voltage across the parasitic impedance. A high impedance voltage measuring device measures a voltage difference between the first and second voltages independent of the parasitic voltage to produce a characteristic voltage representative of the characteristic of the environment.
U.S. Patent Application Publication 2014/0113828 describes electrical, mechanical, computing, and/or other devices that include components formed of extremely low resistance (ELR) materials, including, but not limited to, modified ELR materials, layered ELR materials, and new ELR materials.